Category Archives: Gardening

Neighborhood Mosquito Watch

During a run this week I passed an abandoned, 30-gallon aquarium with easily 10,000 larvae doing their thing (wriggling). I came back later, took some photographs (on my Instagram soon if you’re into that), and then dumped it, sending the larvae to their deaths but also releasing a cloud of perhaps 100 newly-eclosed adults. I suspect the aquarium had been there for years, pumping Asian tiger mosquitoes (Aedes albopictus) into the neighborhood. Given the aquarium’s location at the edge of busy parking lot I’m sure that thousands of people have looked at it and thought, “Huh. Looks like an abandoned aquarium full of dirty water. Next to a Christmas tree. I bet there’s a story there!”, and then moved on with their lives.

Abandoned aquarium with mosquitoes

In case you are unsure what an infestation looks like, the next two photographs show what the adults, larvae, and eggs look like. Asian tiger mosquitoes lay eggs singly on the sides of containers or on moist objects floating on the water. They can last over a year as an egg, waiting for conditions to be just right.

Male Asian tiger mosquito (Aedes albopictus) with larvae

Female Asian tiger mosquito (Aedes albopictus) with larvae and eggs

Here’s a sample of the water I pulled from the tank.

But not all the eggs were Aedes albopictus (there are 60 species in PA alone). Here’s a raft of eggs in the aquarium from a different species (Culex sp.). The raft is lodged on a leaf but normally it just floats around until the larvae pop out. Anopheles (another common genus) has eggs that are deposited singly but float with the help of cute little life preservers.

Raft of mosquito eggs

But that’s not all! Yesterday I found a recycling bin behind a church with similar numbers of larvae. Given the amount of leaves decomposing in the bottom I suspect it has been like this for at least the whole summer. Again, it really is strange that nobody did anything about it. It’s right next to a sidewalk that gets lots of traffic (at least on Sundays) and is probably 10′ away from a playground at an infant/toddler daycare center. Poor kids. (I dumped it.)

Recycling bin with stagnant water

Given how much people hate mosquitoes it left me thinking how the public outreach about mosquito control has failed on the most basic level. Everyone should know enough about mosquito biology to know how and where they breed, and everyone should feel empowered to do something. Being proactive is so much better than adopting what I think is the common view, “Well if the mosquitoes get bad enough I’m sure the government will spray insecticides from planes.

All it would take would be a nicely worded message from a town official to mobilize residents into a mosquito watch. Something like, “If you see mosquito larvae swimming around in a container when you are out walking your dog, please turn the container upside down or alert the owner about it. Thanks.”

For more of my thoughts on mosquito control, please see, “How to rid your yard of mosquitoes.”

Chinese mantids eat monarch butterflies

This post is a PSA for anyone keen on helping monarchs: if you find Chinese mantids (Tenodera sinensis) in your yard, kill them. Below is a photograph of one that had just snagged a monarch visiting my swamp milkweed. The monarch is fine, by the way. After I intervened she flew off, then came back within seconds and resumed ovipositing.

Monarch butterfly captured by a Chinese mantid (Tenodera sinensi

But unless you’re observing your milkweed patch obsessively, you’ll probably never catch a Chinese mantid in the act. But you can infer their presence by piles of monarch wings (i.e., no body attached). No other animal does this to monarchs.

Monarch butterfly wings left by Chinese mantid predation

And caterpillars are just as susceptible. Here’s a Chinese mantid I interrupted just as it was about to strike:

Colin Purrington Photography: Insects &emdash; Chinese mantis with monarch caterpillar

Chinese mantis can be easily distinguished from any of the native mantids by the presence of a yellow dot in between the forelegs.

Chinese mantis (Tenodera sinensis)

If you find an ootheca (egg case) of this species, crush it. The oothecae have an irregular, messy surface that looks like a blob of brown, poorly-applied insulating foam. Oothecae of the native Carolina mantis are much smoother and streamlined (pic).

First-instar nymph of Chinese mantis (Tenodera sinensis) on ootheca

If you’re like most people (including myself), you grew up believing that mantids are a pesticide-free way of reducing garden pests. How could thousands of web sites be wrong?? The truth is, however, that Chinese mantids are so large that they tend to only eat large insects, and that usually means mainly butterflies, not aphids or other species that are tiny. So if you hate butterflies, by all means encourage Chinese mantids in your yard. But if you like butterflies in your garden, kill the Chinese mantids. And don’t just relocate them, even though that seems like the friendly, eco, green, peace-loving thing to do. Moving introduced, invasive species to another location simply facilitates further spread. It’s like transporting your rabid, aggressive pit bull to a different part of the city (“I didn’t want to euthanize it. Maybe it will thrive in a different neighborhood!”).

FYI, Chinese mantids also eat hummingbirds, plus other birds that are even bigger. The authors of that linked paper conclude,

“Our compilation suggests that praying mantises frequently prey on hummingbirds in gardens in North America; therefore, we suggest caution in use of large-sized mantids, particularly non-native mantids, in gardens for insect pest control.”

Italics mine.

Bee and wasp hotels on iNaturalist

If you’re fond of hole-nesting bees and wasps, please join the new “Bee and Wasp Hotels” project on iNaturalist.org to document the guests and hangerson that arrive at your DIY or purchased hotel. Below are 20 of the most recent observations:

Currently the most photographed visitor is the four-toothed mason wasp (Monobia quadridens). But also plenty of mason bees as well as parasites looking for mason bees. There has also been a slug sighting (don’t ask). 

If this sounds fun but you don’t have a hotel, here are my thoughts on building one.